Absorbent fluff and tissue laminate pads for food packaging

ABSTRACT

An absorbent pad has: a first, outer layer comprising a permeable or non-permeable film; a second, outer layer comprising a permeable or non-permeable film, placed on a side of the pad opposite the first, outer layer; a third layer disposed between the first layer and the second layer, and comprising a tissue laminate comprising at least a first ply and a second ply, with at least one chemical agent or system fixed in the third layer and being either activated by contact with or soluble in an aqueous liquid, the at least one chemical agent or system being in a predetermined amount distributed substantially uniformly per unit area of the surface area between the at least first ply and second ply: and a fourth layer disposed between the first layer and the second layer and comprising fluff, with or without a chemical agent or system, the third layer being joined to the fourth layer to serve as a substrate for the fourth layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/952,879, filed Apr. 13, 2018, which issued Jan. 5, 2021 as U.S. Pat.No. 10,882,295, which claims priority to U.S. Provisional PatentApplication No. 62/641,048, filed Mar. 9, 2018, entitled “AbsorbentFluff and Tissue Laminate Pads for Food Packaging,” each of which isincorporated by reference herein, in the entirety and for all purposes.

FIELD

The present disclosure describes more effective food packaging withmulti-layer absorbent pads that utilize the benefits of carbon dioxidegeneration systems or other chemical actives embedded in the pad andinclude a fluff layer made from wood pulp for liquid absorption andother features to improve control of the environment within fresh foodpackages over an expected package life.

BACKGROUND

Fresh meat, poultry, seafood and produce are frequently packaged in amanner that contributes to maintaining their best quality. To achievethe higher levels of quality, manufacturers of food packaging productsconstantly look for ways to address the common contributors to spoiledfood, such as: excess liquid, microbial growth, rancid odors, and poorseal protection.

Preservation of fresh food products may involve slowing microbiologicalgrowth, enzymatic activity, biochemical deterioration, and moistureloss. These may be achieved in part by reduction of product temperatureto near the freezing point. However, chilling alone has a limited effecton preservation of fresh food products. Another strategy may be thecontrol of liquids. Absorbent pads may be made of an absorbent core,layered with polyethylene, polypropylene, or non-woven materials (e.g.,polyolefin, polyester, or polyamide). The non-woven may be polyethylene,polypropylene, polyester, or any combinations thereof. Absorbent padlayers may be enhanced with chemical systems which may deliver agents tothe product or the packaging environment. When these systems targetcolor change, microbial growth, and other food degradation sources, theymay be more effective in protecting the packaged food from thesesusceptibilities.

Among other enhancements is the control of gases in the packageenvironment as in modified atmosphere packaging. Removal or reduction ofoxygen slows growth of aerobic microorganisms indigenous to fresh orminimally processed foods, lipid oxidation leading to off odors, andpigment oxidation leading to color changes and aerobic respirationreactions.

Some prior art packages use carbon dioxide generation systems toinfluence the internal atmosphere of a package. Elevation of carbondioxide in the tissue of food products retards both microbiologicalgrowth and some enzymatic activity. Because of dissolution of carbondioxide gas in muscle, fat and other tissue or mass of packaged foods,and permeation and transmission of the gas through package structures(such as a transparent film cover layer), concentration of this gas inequilibrium with the food is often decreased below the optimum or eveneffective level. This may mean that a generated carbon dioxideatmosphere may not be provided at the desired concentration for the fullexpected product packaging life. The seller or the purchaser mayexperience a shorter product storage life than desired.

Antimicrobials or chemicals that destroy or control growth ofmicroorganisms may be incorporated into the food or on the food surface,or transferred to the food surface or interior from package structures.

In recent years, modified atmosphere packaging (MAP) has beenincreasingly applied for red meat, poultry and fresh cut produce toextend chilled shelf life. Similarly, in recent years, significantquantities of fresh red meat have been centrally packaged intocase-ready form, most often employing a variant of MAP. On the otherhand, most intact cuts of fresh beef and about half of ground beefcontinue to be packaged in retail grocery back rooms.

One prior art example of an absorbent pad used for food preservationusing MAP or traditional tray overwrap is U.S. Pat. No. 9,198,457, whichforms pouches between layers of the pad to hold active chemical agentsin the package. That pad discloses a layered pad structure with a CO2generation system. It uses the structure and order of individual layersof absorbent material to absorb liquid purge from the packaged productand location in the pad of the active agents used for CO2 generation toaffect the performance of the packaging for CO2 generation over time.For example, the individual components of a CO2 generation system can beseparated by separate pockets formed between different absorbent tissuelayers in the structure of the absorbent pad, to be activated atdifferent times and thereby enhance food preservation over an extendedpackage life. U.S. Pat. No. 9,198,457 also discloses that liquid purgethat enters at the bottom of a pad soaks upward through the pad intoother layers that may define the pockets of the active agents used inCO2 generation and that a superabsorbent membrane layer can be used as aseparating layer to delay passage of liquid purge from one layer toanother. This delay may be used to control the timing of CO2 generation.

Another prior art example of an absorbent pad used for food preservationappears in US Pub. No. 2016/0198727, which discloses another approach togenerating and maintaining a desired CO2 atmosphere. Like U.S. Pat. No.9,198,457, US Pub. No. 2016/0198727 makes use of separation ofcomponents used in CO2 generation. It discloses the use of a permeablebottom layer as a primary entry surface for liquid purge and that thequalities of the absorbent layer(s) may affect the diffusion of theliquid purge within the pad once the purge enters. It also considers andsuggests the selection of the solubility and strength of chemicalcomponents placed in layers and used in CO2 generation to determine howfast a chemical will go into a solution and effects on reaction ratewhen one dissolved chemical component later encounters a secondcomponent used in a CO2 generation reaction. This disclosure alsocontemplates use of superabsorbents in the form of a membrane layer,such as a superabsorbent polymer (SAP) laminate. Examples of suitableabsorbent materials disclosed include, but are not limited to,superabsorbent polymer, compressed SAP composite of superabsorbentpolymer granules adhered with one or more binders and/or plasticizers,compressed composite containing a percentage of short or microfibermaterials, thermoplastic polymer fibers, thermoplastic polymer granules,cellulose powders, cellulose gels, an airlaid with superabsorbent, anyfibrous or foam structure that has been coated or impregnated with asuperabsorbent, absorbent structure having one or more starch orcellulose based absorbents, absorbent structure containingsuperabsorbent material formed and/or cross-linked in-situ, or anycombinations thereof.

The present pad offers improvements over these and other known absorbentpads. By extending the shelf life of food products, it provides anopportunity to reduce waste of perishable foods.

SUMMARY

The present pad offers a way to obtain high absorbency and retardmicrobial growth on the surface of or within packaged foods by improvingthe packaging environment of fresh foods. This disclosure describes anabsorbent pad with an architecture comprising at least four layers ofmaterial. The first layer may be permeable or non-permeable, and thesecond layer, placed on the opposite side from the first, may be thesame as the first layer or be different, to serve a different function.Between the first and second layers, the third and fourth layers arepositioned, where the third layer is composed of two or more tissueplies in a tissue laminate, and the fourth layer is of fluff made fromwood pulp. The tissue laminate of the third layer has chemicals and/or achemical system distributed at a defined per unit area rate within thetissue plies laminated. The fourth layer may have an additional chemicalor chemical system embedded in it. The tissue laminate layer may beassociated and/or mechanically joined with the fluff layer to serve as asubstrate for the fluff during manufacturing and in the completed pad.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-described properties, features and advantages of thisinvention and the way in which they are achieved will become clearer andmore clearly understood in association with the following description ofthe exemplary embodiments, which are explained in greater detail inassociation with the drawings, in the form of schematic illustrations ineach case:

FIG. 1 shows a schematic, cross-section diagram of the layers in anabsorbent pad, where the first layer is at the top, making the contactwith the food product, the second layer is at the bottom (normally incontact with a container), and the third and fourth layers (one of whichis a tissue laminate) are positioned between the first and second.

FIG. 1A shows a schematic, pictorial diagram of an absorbent pad withmultiple layers (with layer separation expanded to aid depiction),enclosed in a package that includes a tray and an overwrap film thatdefines a package atmosphere.

FIG. 2 shows a schematic, cross-section diagram of a tissue laminatelayer with a chemical agent or a chemical system distributed in thelayer.

FIG. 3 shows a schematic, cross-section diagram of a pad containingchemically active layers, arranged as the third and fourth layers, oneof which is a tissue laminate layer; here, two adjacent tissue laminatelayers are shown.

FIG. 4 shows a schematic, cross-section diagram of a fourth layer, madeof fluff associated with a tissue-based substrate and, in oneembodiment, carrying a chemical system.

FIG. 5 shows a schematic, pictorial and cross-section diagram of thelayers in an absorbent pad (with layer height expanded to aiddepiction), where the first layer is at the top, for contact with thefood product, the second layer is at the bottom (normally in contactwith a container in which exuded liquid gathers), and the third (tissuelaminate) and fourth (fluff) layers are positioned between the first andsecond layers, and further showing flow of exuded liquids to and withinlayers loaded with two separate components of a chemical system.

FIG. 6A shows a schematic, pictorial and cross-section diagram of thelayers in an absorbent pad as in FIG. 5 , where the third (tissuelaminate) layer is formed by two tissue laminate layers stacked, one ontop of the other.

FIG. 6B shows a variant of the absorbent pad as in FIG. 6A with twotissue laminate layers separated by a fluff layer.

FIG. 7 shows schematically a pad manufacturing process in which a fluffweb and a tissue laminate web are fed together into a nip where theybecome mechanically bonded, such that the laminate web serves as asubstrate for the fluff, enabling the further steps shown to makeabsorbent pads.

FIG. 8 shows a graph of the results of testing of CO2 generation in padswith a fluff layer and an adjacent laminate layer.

FIG. 9 shows a graph of the results of testing of CO2 generation in padswith an alternative fluff and adjacent laminate layer(s) structure.

FIG. 10 shows a graph of the results of testing of CO2 generation inpads with alternative fluff layers and adjacent laminate layer(s).

FIG. 11 shows a graph of the results of testing of CO2 generation inpads with a fluff layer and separate but adjacent laminate layer(s). butwith differences in CO2 system loading. compared to a single laminatecontrol pad.

FIG. 12 shows a graph of the results of testing of CO2 generation inpads with a fluff layer separating two laminate layer(s). but withdifferences in CO2 system loading, compared to a single laminate controlpad.

FIG. 12A shows the rate of CO2 generation for two of the padsrepresented in FIG. 12

DETAILED DESCRIPTION

Overall Absorbent Pad

The absorbent pad discussed in this application is shown in one typicalpackaging use situation in FIG. 1A. As seen in FIG. 1A, the pad 10 isshown schematically and in an exploded view, for convenience inidentifying individual layers in the pad structure. The absorbent pad 10comprises multiple layers and is used in a tray or other container 30,which may support a food item 50 (shown in phantom). The food istypically placed on the pad 10, which in turn is placed on the tray 30).The absorbent pad 10 as shown includes multiple layers: a top layer 22and a bottom layer 24, with at least one laminated tissue layer (whichmay be formed from the lamination of two plies/layers 26 and 27 orplies/layers 27 and 28). Finally, there is a fluff layer made from woodpulp (which may be layer 28 or layer 26, depending on positioning of thelaminated tissue layer). An outer film layer 40 is used as an overwrapof the tray 30, absorbent pad 10 and food item. The protective packagingeffects of the pad 10 may be delivered: directly to an adjacent surfaceof the food item; into liquids that are exuded from the food item andabsorbed into the pad 10 or that are not captured in the pad 10 butremain in the package; or into the atmosphere around the pad 10 and fooditem defined by the outer film layer 40.

Turning to FIG. 1 , the absorbent pad 10 presented in this disclosurecomprises internally at least one tissue laminate layer 300, comprisingat least two cellulose tissue plies 310, 320 or similar absorbent-basedmaterial, e.g., cotton-based material sheet, with the adjacent pliesdefining a volume for chemical loading. The first and second layers 100,200 in FIG. 1 represent the top and bottom of the absorbent pad, wherethe order of the first layer 100 and second layer 200 is interchangeablein use in a package. For instance, the first layer 100 may be the toplayer (as seen in FIG. 1A or 1 ) and for contact with a food product,with the second layer 200 being the bottom layer, normally in contactwith a tray or other container. However, the pad 10 may be inverted;i.e., the first layer 100 may be used as the bottom layer for contactwith a container, with the second layer 200 being the top layer, usedfor contact with a food product. Between the first and second layers arepositioned the third layer 300 and fourth layer 400, as shown in FIG. 1. The third layer 300 comprises the at least one tissue laminate layer,which may incorporate a chemical system or agent, while the fourth layer400 consists of fluff. The third layer 300 may serve as a substrate forthe fourth layer 400 during manufacturing and also in a completed pad.This fourth layer 400 plays a primary absorbent role but may alsocontain a chemical system or agent that may work together with orseparately from the chemicals described in the tissue laminate layers ofthe previously mentioned third layer 300. The third and fourth layers300, 400 are the core of the absorbent facility of the pad 10. Thisabsorbency makes them suitable also to carry one or more chemicalsystems or agents, which may be liquid activated and exhibit carbondioxide generation, super absorption, ethylene scavenging or inhibiting,oxygen scavenging, antimicrobial properties or other useful functions incombination with liquid absorption in food packaging.

It is desirable in controlling a chemical reaction used in enhancingpackaging to coordinate the structure and action of the absorbent pad 10with the associated chemical components, i.e., the active ingredientsused in the pad 10. These components typically are selected to beinactive or largely inactive when not in solution; as they are exposedto liquids that escape from the packaged food, their activity may betriggered. Thus, control of chemical activity may involve keeping addedchemical components out of solution, for some period of the package lifethen selectively wetting them and initiating the planned reaction. Forexample, in a CO2 generating system, there is typically an acidcomponent and a basic component, each of which starts out in granularform and needs to be put into solution. Flow of dissolved agents in orbetween layers may also be part of bringing together the acid and basecomponents, when their granular (largely dry) forms are separated in thepad structure. So both the step of putting agents into solution andbringing together the dissolved agents present opportunities to controlthe reaction rate leading to CO2 generation.

The absorbent core material used in a layer and designed to eithercontrol exuded liquid by absorption and/or control liquid interactionwith a chemical system or agent may comprise any material suitable forabsorbing liquids, particularly food-product liquids. In the paddisclosed, fluff made from wood pulp, which is known as a good absorbentmedium in other situations, is used. The fluff can be treated with asuperabsorbent material, to increase its natural absorbent properties. Aprimary issue with fluff is that in relatively thin layers it is notsuitable for many high-speed sheet or roll manufacturing processes, suchas are typically used for absorbent pad manufacture. Fluff won't easilycut without the tissue laminate layer to carry it through a knifestation. Most, and particularly thicker, fluff mats without a substratewill compress at the knife section rather than be cut. It has been foundin the present design that use of a tissue laminate layer, as opposed toa typical carrier sheet, helps to carry the associated fluff through themanufacturing process, in particular through a knife station whereslitting occurs, while also providing the added opportunity to introducevarious chemical agents or systems in a uniform and controlled manner.

With this overview, the nature of each layer combined for the presentdisclosure is described next.

Layer 1. The first layer 100 of the claimed pad, as shown in FIG. 1 , ismade from a film (permeable or non-permeable) that, in one embodiment,comes into direct contact with a food product to be packaged. This layermay be impermeable to aqueous fluids that escape or exude from the foodproduct, such as water, saline, seawater, juices or blood. In someembodiments, the first layer 100 comprises an impermeable film. It maybe impermeable to moisture. It may comprise, consist essentially of, orconsist of polyethylene film in a thickness from 0.5 to 3 mil. The firstlayer may also consist essentially of, or consists of polypropylene filmin a thickness from 0.5 to 3 mil. In other embodiments, the first layercomprises, consists essentially of, or consists of polyester or apermeable material such as a non-woven material (e.g., of one or moreof: polypropylene, rayon, polyolefin, polyethylene, and/or polyester).The top or bottom layers may also be made of wet strength cellulosematerial. In some embodiments, the permeable material of the first layercomprises a nonwoven material in a weight from 15 to 50 GSM. Thisnonwoven material may include a hydrophilic surface treatment to makethe non-woven material more permeable to liquids, particular aqueousliquids. Examples of suitable hydrophilic surfactants includesurfactants (polyolefins), surface oxidation, electrostatics, plasmatreatments, fatty acids, or other cationic, anionic, amphoteric,nonionic surfactants. Permeability of an outer layer of the pad makes itan easy surface through which an exuded liquid can enter the pad. Inaddition to surfactants, perforations can be used to increase layerpermeability to exuded liquids.

Layer 2. The second layer 200, as seen in FIG. 1 , is also made from afilm (permeable or non-permeable) that can be the same as or differentfrom the film used in the first layer. In one embodiment, the secondlayer is for contact with a tray or other container. In someembodiments, the second layer is permeable or substantially permeable toaqueous fluids that escape from the food product, such as water, saline,seawater, juices or blood. In some embodiments, the second layercomprises, consists essentially of, or consists of a nonwoven film. Asused herein, the term “nonwoven film” refers to a substantially flat,porous sheet made from fibers or molten plastic/plastic film (e.g.,without converting the fibers or molten plastic/plastic film into threador yarn) in a weight from 15 to 50 GSM. In some embodiments, the filmcomprises, consists essentially of, or consists of one or more of:polypropylene, rayon, polyolefin, polyethylene, and/or polyester in athickness from 0.5 to 3 mil. In some embodiments, the second layercomprises, consists essentially of, or consists of a non-permeablematerial including a plurality of one-way fluid valves, which may be inthe form of perforations formed by a pin wheel or other suitable means.The second layer may also be a wet strength cellulose material.

Layer 3—Tissue Laminate. As seen in FIG. 1 , the third layer 300 may bepositioned between the first layer 100 and the second 200. It maycomprise a cellulose tissue laminate. The lamination of the layers mayin one embodiment be formed by adhesive/glue ply bonding. Food gradesadhesives are used, such as thermoplastic hotmelt, water based pressuresensitive adhesives, polymeric adhesives, or metallocene adhesivesavailable from Henkel, HB Fuller, Bostik or Savare.

This laminate 300, as seen in FIG. 2 , may comprise a first tissue layeror ply 310 and a second tissue layer or ply 320, which between theiradjacent surfaces may contain one or more chemicals comprising achemical system or agent 330. The chemical system or agent 330, as shownin FIG. 2 , may be distributed in a volume formed by lamination of theplies, which may increase the bulk of the two tissue plies, and may be asystem or agent of various kinds found useful for improving productshelf life. It is preferred that the position of any chemical systems oragents in the laminate be stable or fixed, such that any particlesembodying the chemical systems or agents do not migrate significantlyfrom their positions as placed in the laminate 300. This may beaccomplished in whole or in part by the embossing and/or pressureemployed for lamination. It may also be accomplished by glues oradhesives that fix the added particles or by applying an agent in liquidform to a tissue or to laminated tissues and allowing it to be absorbed,with or without drying. Alternatively, an optional adhesive layer 312applied, for example, to tissue layer 310 or mixed with the agent 330,may help hold the agent 330 in place. In one embodiment, the system oragent 330 may comprise: an antimicrobial (e.g., citric acid and sorbicacids mixed in about a 64.5:35.5 ratio or ClO2, molecular iodine, Agbased systems, or Cu based systems; carbon dioxide generating chemicalsconsisting of acid and base in ratio of about 43/57; or an ethylenescavenger or inhibitor. Further details of the chemical systems oragents in a tissue laminate 300 are discussed below. These can be in anycombination and are typically separate from any chemical systems thatmay be placed in layer 4, the fluff layer 400 in FIG. 1 .

Tissue laminate layer 300 may comprise more than two plies or layers oftissue laminated together, as depicted in FIG. 3 . In the embodiment ofFIG. 3 , a first pair of laminated tissue plies 310, 320 fixed withfirst chemical agent or system 330 is further laminated with a secondpair of laminated tissue plies 340, 350 with second chemical agent orsystem 360, placed between the additional plies 340, 350. This allows achemical system to be separated into two components that have little orno contact until liquid in one or both of the components dissolves oneor both and the dissolved components flowing together activates theirreaction. (As discussed below, stronger separation for controllingdissolution can be effected with a fluff layer between two tissuelaminates.) The first and second pairs of laminated tissue plies alsoallows a chemical system to be duplicated to increase its effect in onetime interval, or where liquid that activates the systems is controlledto delay its entry into one chemical system or the other of two tissuelaminates with spatial separation or separation by a fluff layer, toprovide the same chemical effect at a different, later time. The firstand second chemical agents or systems 330, 360 also may be different andprovide two different chemical effects. Again, where liquid thatactivates the systems is controlled as to the time it contacts the firstand second chemical systems 330, 360, the two different chemical effectsmay be provided at the same time, at different but overlapping timeperiods or at separate and different time periods. As with the firstpair of laminated tissue plies 310, 320 with first chemical system 330,the particles or other material comprising the chemical system or agentmay be made stable or fixed in tissue plies 340, 350 by methodsdescribed above.

Each tissue laminate 310, 320 or 340, 350 is preferably a part of theabsorbent core body of the pad 10, combining tissue layers withabsorbent capacity and/or other absorbent material, such as the SAP,discussed above. In most applications, a tissue laminate cannot be theentire absorbent body. In one embodiment, the laminate is made of one ormore plies or layers of light or heavy weight crepe wadding materialwith a glue or an adhesive or other binder between layers. Heavy crepetissue has a crepe percentage of about 70%, mid-grade is about 40-50%and flat grade is less than about 10%. Examples of suitable glues oradhesives for a cellulosic tissue laminate include thermoplastichotmelt, water based pressure sensitive adhesives, polymeric adhesives,or metallocene adhesives available from Henkel, HB Fuller, Bostik orSavare. In an exemplary embodiment of absorbent pad of the presentdisclosure, the laminate 300 is a mixture of cellulosic material and onechemical agent or system based on the specific application for the pad.

A tissue laminate offers several advantages for an absorbent pad thatalso carries a chemical system or agent. First, a laminate canincorporate large amounts of an active agent in a relatively thinstructure (using, if needed, optional adhesive (e.g., FIG. 2 , at 312)or other fixing methods described above), while avoiding thedisadvantages of having large amounts of dry, loose chemicals in a padthat can cause an absorbent pad to “bulge” and/or have active agentsthat collect disproportionately in one portion of the absorbent pad whenthe absorbent pad is picked up by one edge or subjected to vibrationsand/or orientations that disrupt an initial uniform distribution ofloose chemical particles. Second, because an active agent or system canby a metering roller, metered spray or other controllable dispersionmeans be uniformly distributed at a desired rate per square unit of areain a laminate and held in place with an adhesive, or other fixingmethods, if needed, selecting a prescribed distribution area and adefined or predetermined distribution rate per unit area and selecting anumber of plies of the laminate permits the total amount of active agentto be determined with accuracy on a per unit of laminate area basis.Further, the position of the active agents remains predictable aftertheir placement. In effect, the laminate becomes one tool for meteringthe desired amount of chemical activity capacity into a layer and padand controlling the interaction of chemical agents or of the agentsdissolved in an aqueous liquid used to activate them. (The adjacentlayers may provide a second tool to control the flow of aqueous liquidswithin the pad structure.) An exemplary embodiment of laminate use in apad is a cellulosic tissue material and CO2 generating components plusan antimicrobial that is uniformly distributed therein to form one ormore plies of the laminate. Such an embodiment is effective to inhibitbacterial growth within the pad structure and generate CO2 gas toinhibit bacterial growth on the surface of the meat by interfering withbacteria reproduction and biochemical pathways. Assuming adequate liquidfor activation delivered by flows into the pad and between layers, thedeposited chemical system will perform its function over the entire areawhere it was placed and fixed in the laminate. Where a two-componentsystem is separated in two layers, a designed coordination orcomplementarity of the two layers can be effected and maintained byprecise metering and placement of components in a laminate. For example,a selected amount of a component in one layer can be fixed in locationrelative to a designated amount of a paired component in an adjacentlayer or coordinated to expected liquid flow or absorption in a layer.This may help reduce the amount of chemicals left unreacted or not usedfor their intended purpose in a pad structure.

The two tissue layers 310, 320 shown in FIG. 2 may have chemicalsembedded in and/or between them by the methods described above. In oneembodiment, these laminates are constructed using 2 plies of flat grade,or similar grade, tissue in the range of 14-20 lb./3000 ft{circumflexover ( )}2 sheet). The layered, laminated tissue, described previously,may take the form of one or more laminated layers, each consisting oftwo of more tissue plies. The tissue layers may be composed ofcompostable polymers or compostable polymers derived from cellulose orpaper-based materials originating from wood fiber, such as cellulose.Tissue layers may take the form of tissue in sheet or roll form for padmanufacturing, with roll being the preferred format. The tissue layersmay be bleached or natural (unbleached). Processed tissues such ascoffee filter tissue (CFT) may also be used. The tissue laminate layerof a pad will be formed prior to and/or separately from the otherlayers, so that it is available in a completed form for use as asubstrate for the wood pulp fluff layer 400 described next, as it entersa high-speed manufacturing process.

Layer 4—Fluff. As seen in FIG. 4 , the fourth layer 400 may be of flufffrom wood pulp, such as 100% virgin pine pulp available from GeorgiaPacific or International Paper. Wood pulp is received in a 1-2 mmthickness sheet. The wood pulp is put in a hammer mill to create fluffto increase pulp absorbency. The final product made from the wood pulpis a fluff web, typically 0.25-3.0 inches in thickness. In the padsdescribed herein, a layer of fluff (processed pulp) 400 is placedadjacent and joined to the tissue laminate layer 300 at an early stageof pad manufacture, so as to form a mechanical bond between the two.This fluff layer comprises, consists essentially of, or consists offibrous fluff and can be constructed of a combination of fibrous fluffand other materials such as: superabsorbent materials, surfactants, orother active type ingredients. Fluff as used in a pad of the presentdesign provides one or more benefits, including: 1) more consistentabsorbency under load than tissue; 2) closer control of the absorbencylevel by selection of thickness and weight; 3) better moisturedistribution (moisture moves in x, y, and z dimensions) than tissue; and4) better wicking and speed of absorbency. From a processing efficiencystandpoint, using fluff reduces water consumption relative to formingtissue as the absorbent.

For purposes of manufacturing a pad 10, it is advantageous to use thetissue laminate layer 300 as a substrate for carrying the fluff into theroll manufacturing process used to form the core and to slit and carrythe fluff through the subsequent steps of the pad manufacturing process.A typical wood pulp fluff sheet lacks tensile strength and is easilycompressed and thus by itself is not easily handled in manufacturingequipment for making pads. This may be addressed by joining the fluffwith a substrate, in one embodiment a tissue laminate as describedabove, at the time the fluff sheet enters the manufacturing process. Forexample, a sheet of fluff in roll (web) form may be fed at the same rateas a sheet of tissue laminate in roll form, with the two compressedtogether at a nip to form a mechanical bond. In one embodiment, thelaminate joined with the fluff is made with a light crepe paper in therange of 9-20 lbs./3000 ft² sheet. The creping may help create a type ofmechanical bond, causing the fluff to adhere to the tissue laminatesubstrate. In the manufacturing process, the substrate or carrier sheetcomes in on top of the fluff layer as soon as it is formed as a web atthe exit of the hammer mill. Atmospheric humidity or misting may be usedat the time of joining the fluff and laminate to enhance the bond. Thesubstrate carries the fluff through the exit of the hammer mill andthrough the later stations for combining with the webs that form top andbottom layers of a pad. It should be noted that in one embodiment thetissue laminate layer is fully formed, including any chemical loading ofthe laminate, before it is used as a substrate.

As shown in FIG. 4 , the fluff layer 400 may contain one or moreadditional chemical systems 410, similar to, or the same as, the onesdescribed for tissue laminate layer 300. The chemicals of the chemicalsystems may be applied to and in the fluff layer 400 by dispersingchemicals into the sheet-forming chamber with wood pulp fibers. Theamount of CO2 system or other chemicals added into the fluff will bebased on the weight of the fluff in the pad, rather than on the persquare unit rate used for tissue laminates (although a fluff sheetitself may be specified by its weight per square unit). For example, afluff layer may have 0.15% chemical added by weight of fluff up to 50%chemical added by weight of fluff. The amount of fluff used in the padvaries by application, depending on both the absorbency target for thepackage as well as the chemical loading, which will in some embodimentsbe a superabsorbent material added to help achieve the absorbency targetor provide liquid control. While the tissue laminates have someabsorbency, they are used mainly to hold chemicals and transfer liquidsto activate chemicals, and they do not add significantly to theabsorbency capacity of the pad, above what the fluff layer provides.These fluff-hosted chemical systems may or may not be used inconjunction or coordination with the chemical systems in the laminatelayer 300. In effect, like the tissue laminates, the fluff layer mayalso become a tool for metering the desired amount of chemical activitycapacity into a pad.

Providing a chemical system in a fluff layer allows a chemical systemalso placed in a tissue laminate layer to be duplicated, to increase itseffect in one time interval, or where liquid that activates the systemsis controlled to delay or accelerate its entry in one chemical system orthe other, to provide the same chemical effect at a different, latertime. Again, where liquid that activates a chemical system in a flufflayer is controlled as to the time it contacts the first and secondchemical systems 330, 360, the two different chemical effects may beprovided at the same time, at different but overlapping time periods oras separate and different time periods. Use of a superabsorbent materialin one layer, e.g., a fluff layer, increases absorbency in that layerand can be used to control flow of a liquid into a layer that isdownstream, based on the structure of a pad and its surfaces for liquidentry. Use of a tissue laminate substrate 401 as further described belowmakes it possible to use the fluff layer in high speed web manufacturingprocesses of pads.

Chemical Systems

Many chemical systems or agents can be integrated into the absorbent padto achieve results of high absorption, lower bacterial growth rates, andbetter structural integrity of packaged food products. Among thosechemical systems are CO2 generating systems, activated carbon or otherodor absorbing compounds, antimicrobials, oxygen scavengers, andethylene scavengers or inhibitors. Examples of how these systems workinside the absorbent pad are given below.

Activated carbon. Activated carbon is a solid, highly porous materialthat captures, adsorbs and traps volatile organic compounds on itssurface. Activated carbon captures organic compounds from gas and liquidstreams, and so is commonly used in filters as an economical way toremove organic contaminants from large volumes of air or water. Theprimary use for activated carbon is treatment of water, includingpotable water, wastewater, and groundwater remediation. Activated carbonis generally safe for human ingestion, and has been used as anodor-removing, color-removing, and taste-removing agent in foodprocessing.

Activated carbon largely adsorbs, as opposed to absorbs, molecules oforganic compounds. Adsorption is a process by which molecules adhere tothe surface only. Absorption, by contrast, is analogous to a sponge thatsoaks up water, in which the absorbed water is fully integrated into thesponge. Activated carbon has a large adsorption-available surface areaand pore volume that gives it a unique adsorption capacity. Commercialgrade activated carbon for food products has a surface area that rangesbetween 300 and 2,000 m2/g, with some having surface areas as large as5,000 m2/g. Activated carbon adsorbs molecules of odor-causing organiccompounds, for example, as these compounds “stick” to the surface of thecarbon particles along this very large surface area.

Activated carbon captures and adsorbs organic compounds much morereadily than it attracts and adsorbs inorganic compounds. Hence, fewinorganic compounds are removed by filters that contain activatedcarbon. Molecular weight, polarity, water-solubility, temperature andconcentration affect the capacity of activated carbon to capture aparticular compound.

In one exemplary embodiment, the tissue laminate is a combination ofcellulosic material, activated carbon, and an antimicrobial. In apreferred embodiment, the antimicrobial is an organic acid orcombination of organic acids. The activated carbon or the antimicrobialmay be included in a sandwich layer between two tissue plies as seen onFIG. 2 or FIG. 3 , or one of both of the activated carbon orantimicrobial may be loaded into a tissue laminate when the tissuelaminate is formed. Possible antimicrobials chemicals include organicacids, silver based antimicrobials, and copper based antimicrobials.

CO2 generation. An exemplary embodiment of a CO2 generation system is anacid and a base, such as citric acid and sodium bicarbonate,respectively, that react with each other (when activated by water orother aqueous liquid) to generate CO2 gas. The acid component of the CO2generation system can be a food safe organic acid (that includes, but isnot limited to, citric acid, sorbic acid, lactic acid, ascorbic acid,oxalic acid, tartaric acid, acetic acid, and any combinations thereof)and inorganic acids (such as boric acid). The ratio and amounts of acidand base, as well as their physical placement in the pad architecture,can be varied to control the timing and amount of CO2 released. In oneexemplary embodiment, citric acid and sodium bicarbonate are present inan absorbent body (tissue laminate or fluff) in a ratio of about 43:57,e.g., 43% citric acid and 57% sodium bicarbonate, which can be activatedby moisture and/or other aqueous food exudates to generate CO2 gas.Citric acid provides an additional benefit by interacting with thesodium ion of sodium bicarbonate to create a citric acid/sodium citratebuffer system that helps maintain a pH that is food-compatible. Otheracids can be selected for a CO2 generation system, with amounts andratios adjusted in accordance with the pKa of the acid.

Ethylene agents. Examples of an ethylene inhibitor or ethylenecompetitor agents include, but are not limited to, 1-methylcyclopropene,(also called “MCP” or “1-MCP”), its salts and chemical derivatives. Theone or more ethylene competitor agents can be selected to bindirreversibly to the ethylene receptors. Additionally, the system caninclude an ethylene scavenger which adsorbs ethylene given off by thefruit or surroundings. Ethylene promotes ripening and the onset of themold botrytis.

Oxygen scavengers. In one exemplary embodiment, the absorbent pad hasactivated carbon and an oxygen scavenging enzyme. The activated carbonand oxygen scavenging enzyme can be disposed in absorbent body, such asa tissue laminate. In a preferred exemplary embodiment, an absorbent padhas activated carbon and the oxygen scavenging enzyme(s) glucose oxidaseand/or catalase in various layers. The active carbon would likely workin conjunction with a CO2 generator or an antimicrobial or possibly anoxygen scavenger but be less effective with an ethylene inhibitor andscavenger.

In yet another exemplary embodiment, an absorbent pad has activatedcarbon, an oxygen scavenging enzyme, and an antimicrobial agent. Theactivated carbon, oxygen scavenging enzyme, and antimicrobial agent canbe disposed in an absorbent body, or in a tissue laminate. In apreferred exemplary embodiment, an absorbent pad has activated carbon,oxygen scavenging enzyme(s) glucose oxidase and/or catalase, and theantimicrobial agent(s) citric acid and/or sorbic acid.

For those embodiments of an absorbent pad having an oxygen scavengerenzyme, the absorbent pad can have additional active agents, like anantimicrobial.

As seen in FIG. 3 , each active agent/active system can have itscomponents be positioned in a volume available in an absorbent pad layerthat is formed by: any two laminated tissue layers (e.g., layer 3; 300);any tissue layer and an adjacent laminate; topmost tissue layer and topouter layer 100; and/or bottommost tissue layer and bottom outer layer200. Alternatively, an active agent can be incorporated in one or moreplies of a laminate as seen in FIG. 2 or FIG. 3 . In one embodiment,each of the two components of a CO2 generation system is placed in atissue laminate layer, each of which may be formed from two or moretissue plies, joined by an adhesive. In another example, each of the twoCO2 chemicals plus an antimicrobial is in a tissue laminate incorporatedinto a pad containing also a fluff layer with a superabsorbent materialdispersed in the fluff. The CO2 chemical system will be at the top ofthe pad closest to layer 100 in FIG. 3 . Fluff with a superabsorbentmaterial may be in layer 400 closest to layer 200. Activation will occurthrough layer 200 and the superabsorbent material will absorb liquidbefore activation of the top chemically-loaded tissue laminates canoccur. Fluff and a superabsorbent material can be increased for thespecific application to add more or less absorbency to increase ordecrease activation time.

Examples. FIG. 5 shows in schematic form an example of one embodiment ofan absorbent pad in which a layered structure is used to control CO2generation. As seen in FIG. 5 , the absorbent pad 511 comprisesinternally at least one tissue laminate layer 540, comprising at leasttwo cellulose tissue plies 510, 520, with a chemical agent 530distributed in granular form between the plies 510, 520 and fixed withan adhesive. The first and second layers 100, 200 in FIG. 5 representthe top and bottom outer layers of the absorbent pad 511. These outerlayers 100, 200 are as described above in connection with FIG. 1 . Forinstance, the first layer 100 may be the top layer (as seen in FIG. 1 )and for contact with a food product, with the second layer 200 being thebottom layer, normally in contact with a tray or other container.Between the first and second layers are positioned the third layer 540and fourth layer 400, as shown in FIG. 1 . The third layer 540 comprisesthe at least one tissue laminate layer, which may incorporate onecomponent 530 of a chemical system for CO2 generation, while the fourthlayer 400 consists of fluff 410 loaded with the other component 420 of achemical system for CO2 generation. The graph of FIG. 8 shows some testresults of ways of placing the chemical agents with a CO2 generatingfunction in a pad with the general structure of FIG. 5 and having oneouter layer that is permeable. The tests were compressed, performed overa period of hours shorter than a typical food product package life butlong enough and with enough liquid supplied (metered into each structurein defined amounts at defined intervals), identical for each structure)to show CO2 generation behavior. It can be seen that the differentstructures identified with different lines lead to differentiation ofassociated CO2 generation curves. These demonstrate that the differentstructures allow control of the rate of CO2 generation over time andalso to some extent the total amount of CO2 generated. The dotted andsolid lines in FIG. 8 show the CO2 generation curves for pads with thecomplete CO2 generation system loaded into the laminate, but with apermeable outer layer closest in one test and a non-permeable outerlayer closest in the other test. The dashed line and the dash-dot linesboth correspond to structures realizable as in FIG. 5 , with a CO2system separated by placing one component in the fluff and one in thelaminate. The different locations of the acidic and basic componentslead to even further differentiation of associated CO2 generationcurves. Again, the results demonstrate that the variations in chemicalloading possible in this pad architecture allow control over CO2generation, both amount and rate.

FIG. 5 shows only a few symbolic granules of chemical component 530 inthe volume between plies 510, 520, which would be occupied by a uniformlayer of component 530 with a predetermined distribution rate per unitarea and is shown with an exaggerated relative thickness. Similarly,FIG. 5 shows only a few symbolic granules of component 420 in the volumeof fluff 410, which would be occupied by a distribution of component 420in the fluff 410. The third layer 540 (tissue laminate) also serves as asubstrate for the fourth layer 400 during manufacturing and in acompleted pad. The fourth (fluff) layer 400 plays a primary absorbentrole in the pad 511 but may also contain at least one chemical component420 that may work together with the chemical 530 described in the tissuelaminate layer of the previously mentioned third layer 540; e.g., thetwo generate CO2 when dissolved together. The fourth layer 400 may alsobe loaded with additional chemicals. For example, it may incorporatesuper absorbent material to meet an absorbency target or to help retardmigration of absorbed liquid into the third layer 540 to delay CO2generation. The graph of FIG. 9 shows results from use of the same testprotocol as the tests for FIG. 8 , but here the fluff layer is loadedwith two different loading levels of a superabsorbent material. Thediffering results show that the structure of FIG. 5 combined withvarying the loading level of superabsorbent material allows a form ofcontrol over CO2 generation curves. This likely is obtained by thesuperabsorbent material delaying liquid migration. The fourth layer 400may also incorporate an antimicrobial.

FIG. 5 also shows exuded moisture or liquid entering the pad 511 throughbottom layer 200 (flow 512) to disperse (arrow 514) and be absorbed influff 410 and to dissolve CO2 component 420. That liquid moves throughthe fluff 410 to enter and disperse (flow 516) in the tissue laminatelayer 540 and bring dissolved CO2 component 420 into contact with theCO2 component 530 distributed throughout laminate layer 540.

The flows of liquid within the pad show the possibility of other controltools for activation of chemical agents and systems possible with thepad architectures disclosed herein. It has been noted that a fluff layerand a tissue layer have somewhat different liquid transport tendencies.Fluff has void spaces and absorbs in the “x” and “y” directions (i.e.,in the plane of the fluff layer before it absorbs and transports liquidin the “z” direction. By contrast, tissue absorbs preferentially in the“z” direction (i.e., a direction perpendicular to the plane of thetissue layer) before it transports liquid in the “x” and “y” directions.This also can play a role in chemical component loading strategies forthe pad architectures disclosed herein, leading to differentiated CO2generation curves, which may be more or less suitable for particularapplications.

FIG. 6A shows in schematic form another embodiment of an absorbent padin which a layered structure is used to control CO2 generation. As seenin FIG. 6A, the absorbent pad 611 comprises internally two tissuelaminate layers 540A, 540B. Layer 540A comprises at least two cellulosetissue plies 510A, 520A, with a chemical agent 530A distributed ingranular form between the plies 510A, 520A and fixed with an adhesive.Similarly, layer 540B comprises at least two cellulose tissue plies510B, 520B, with a chemical agent 530B distributed in granular formbetween the plies 510B, 520B and fixed with an adhesive. The first andsecond layers 100, 200 in FIG. 6 , as in FIG. 5 represent the top andbottom outer layers of the absorbent pad 611 and are as described abovein connection with FIG. 1 . This structure shows how two separate CO2generating tissue laminates 540A, 540B can be used to place each of thetwo CO2 generating components in separate tissue laminate layers or toduplicate the chemical potential of one tissue laminate by placing twolaminates with duplicated chemical loads adjacent to each other. Thefluff layer 400 is not used as part of CO2 generation and can then beloaded with an agent 620, such as super absorbent material, to meet anabsorbency target or to help retard migration of absorbed liquid intothe tissue laminate layers 540A, 540B to delay CO2 generation longerthan the structure of FIG. 5 . Layer 400 may also incorporate adissolvable antimicrobial in place of or in addition to super absorbentmaterial 620.

As can be seen in FIG. 6A, exuded liquid enters the pad 611 throughbottom layer 200 (flow 612) to disperse (arrow 614) and be absorbed influff 410 and to be absorbed in component 620, if it is super absorbentmaterial, or to dissolve a non-super absorbent material component. Thatliquid moves through the fluff 410 to enter and disperse (flow 616) inthe lower tissue laminate layer 540B then upper tissue laminate layer540A. This brings dissolved CO2 component 530B into contact with the CO2component 530A distributed throughout laminate layer 540A. The mixing ofdissolved CO2 components 530A, 530B (acid+base) leads to CO2 generation.The CO2 travels through the layer 100, which may be a permeable side ofthe pad, to deliver CO2 590 into the package atmosphere above the pad611.

In a structure such as in FIG. 6A, the amounts of CO2 componentsseparately fixed in tissue laminates 540A, 540B can be more preciselymatched for uniform distribution, such that it is more likely that(assuming adequate liquid) substantially all of each CO2 component (acidor base) will participate in a CO2 generating reaction. In oneembodiment, the following loading amounts are suitable for CO2generating components in this structure:

Weight/in. sq. of acid component for CO2 (0.042 g/in{circumflex over( )}2)−43% of CO2 system

Weight/in. sq. of base component for CO2 (0.0557 g/in{circumflex over( )}2)−57% of CO2 system

It will be seen that the same structure with two tissue laminate layers540A, 540B can be loaded such that the lower tissue laminate 540B can beused with fluff layer 400 to hold the two CO2 generating components inthe same manner as described for the single tissue laminate layer 540and fluff layer 400 in FIG. 5 . If this is done, top tissue laminatelayer 540A is available for other purposes. For example, it may beloaded with both CO2 generating components, which can be used as adelayed release CO2 generating source, which will not be fully activateduntil sufficient liquid has moved up through both fluff layer 400 andlower tissue laminate 540B. As an alternative, top tissue laminate layer540A is available for use to load an antimicrobial or other chemicalsystem discussed above. In one embodiment, the following loading amountsare suitable for antimicrobial components in this structure:

Weight/in. sq. of antimicrobial (AM) component (0.0265 g/in{circumflexover ( )}2 total); citric component=0.071 g/in{circumflex over ( )}2(64.5% of AM component); sorbic component 0.0094 g/in{circumflex over( )}2 (35.5% of AM component);

In a further embodiment based on the pad architecture of FIG. 6A, bothCO2 components and a superabsorbent material, with or without additionalcomponents, can also be added to one laminate layer (or to both) and thefluff can deliver moisture to one or both laminate layers. Increasingsuperabsorbent material in the laminate in combination with the CO2chemicals will allow for more CO2 generation later in the package life,because the superabsorbent material tends to release some absorbedmoisture over time, allowing for more liquid to be available forreaction later in the package life. This is illustrated by test resultsshown in FIG. 10 . The graph shows results from different padsrepresented by dotted, dashed and dot-dash lines showing CO2 generationfor pads with different superabsorbent loading.

The above numbers are all based on the area of a tissue laminate layerused in a pad and do not include loadings into a fluff layer, whichwould have a different specification based on fluff weight.

The examples shown in FIGS. 5 and 6A, show the flow of liquids into thelayers with chemical systems from a bottom liquid-permeable layer up, toshow one form of controlled activation of layers based on an upwardliquid migration. It will be seen that in other examples andapplications a pad may have another permeable layer at the top and openedges in the pad layers. This would allow in-from-the-top in addition toor in place of in-from-the-bottom flows in the pad, and/or liquid flowsinto the sides of various layers. These structural alternativesavailable in the disclosed pad allow other chemicalperformance-over-time curves to be achieved with the disclosed padarchitectures.

In another variant of layer architecture, the layers as shown in FIG. 6Amay be rearranged so that the fluff layer 400 is sandwiched between abottom laminate layer 540B placed below the fluff layer 400 and a toplaminate layer 540A placed above the fluff layer 400. This configurationis shown in FIG. 6B.

The following are other possible variations of structure for the padsdisclosed above:

Two or more tissue/chemical laminates can be incorporated into the padat once making the pad five or more layers. Tissue laminates can be anymixture of CO2, antimicrobial, super absorbent material, odor absorbentmaterial, O2 scavenger, ethylene scavenger or inhibitor or any systemalone.

The absorbent pads disclosed above, wherein the third layer comprises,consists essentially of, or consists of a tissue laminate that containsa CO2 generator, wherein said CO2 generation system is an acid and abase.

The tissue laminate layer disclosed above, consists of two layeredtissues with CO2 generating chemicals containing an acid and a base inthe ratio of 57% base and 43% acid.

The CO2 generating chemicals disclosed above can consist of any of theseacids: Citric acid, fumaric, ascorbic, maleic, or malic, or anycombination.

The CO2 generating chemicals disclosed above can consist of the basessodium bicarbonate, calcium carbonate, or like base.

The CO2 generator from an absorbent pad disclosed above provides abacteriostatic effect on the protein in the package by interfering withbiochemical pathways of bacteria preventing reproduction and thereforeextending shelf life by reducing surface bacteria.

The absorbent pad disclosed above, wherein the third layer comprises,consists essentially of, or consists of a tissue laminate that containsan antimicrobial.

The antimicrobial in a pad disclosed above consists of citric acid andsorbic acid in a 64.5/35.5 ratio. Antimicrobials can also be Ag based,molecular iodine, ClO2, Cu based.

The antimicrobial in a pad disclosed above is a bacterial inhibitor thatenhances food safety of the food package.

The absorbent pad as disclosed above, wherein a layer comprises consistsessentially of, or consists of a tissue laminate that contains a superabsorbent polymer or super absorbent fiber.

The super absorbent polymer disclosed above consists of a food-safehydrophilic polymer such as optionally cross-linked polyacrylate.

Once the liquid is absorbed into the core of pad disclosed above, thesuper absorbent draws moisture toward the chemical systems initiatingactivation or can delay activation, based on the structure.

An absorbent pad as disclosed above, wherein the third layer comprises,consists essentially of, or consists of a tissue laminate that containsan oxygen scavenger. The oxygen scavenger is an enzymatic system. Theenzymatic system is glucose oxidase. The oxygen scavenger starvesbacteria of oxygen, inhibiting growth and therefore extending shelf lifeby reducing surface bacteria.

An absorbent pad as disclosed above, wherein the third or fourth layercomprises, consists essentially of, or consists of a tissue laminatethat contains an ethylene scavenger or inhibitor.

An ethylene inhibitor used in a pad disclosed above is a sugar basedpowder containing 1-MCP or is a silver based powder.

An absorbent pad as disclosed above, wherein the fourth layer comprises,consists essentially of, or consists of fluff that contains anantimicrobial, CO2 generator, oxygen scavenger, odor absorbent material,ethylene scavenger or inhibitor, or super absorbent polymer or superabsorbent fiber.

An absorbent pad as disclosed above utilizes a reaction promoter thatcould be water, saline solution, blood, or protein enhancement solution

The control of pad performance for liquid absorption and/or transportand for chemical activation and/or reaction that is possible with theabove disclosed structures is further illustrated in comparative testresults for different chemical loading strategies using the abovearchitecture with fluff and tissue laminate layers. FIG. 11 showsresults from an absorbent pad as shown in FIG. 6A in which the completeCO2 generating system has been replicated, to provide twice the chemicalload of a pad with just one laminate, in each of the two separatelaminates 540A and 540B. This increases the overall generation of CO2.The increase can be adjusted with precision, because of the ability touse the defined or predetermined, uniform distribution rate per unitarea in a tissue laminate to select the amount of CO2 generationcapacity to be added with a given area of tissue laminate. FIG. 11 showsalso results from another embodiment of the pad of FIG. 6A, in which thetwo CO2 generating components have been separated into adjacentlaminates 540A and 540B. This was found to delay the generation of CO2and further control the generation profile as may be needed for certainapplications. The resultant CO2 generation profiles can be seen in FIG.11 , in which the solid line is results from a pad with a CO2 systemcontained in a single laminate (control), the dotted line is resultsfrom a pad with the CO2 system replicated in two laminates, and thedashed line is results from a pad with the two CO2 system componentsseparated into adjacent laminates.

FIG. 12 shows results from use of structures as in FIG. 6B with acomparison to a control pad having a complete CO2 system in onelaminate. Here the configurations tested included not only loading ofthe CO2 generating components but also the use of a superabsorbents as away to control liquids released within a package. The pad configurationstested (using a compressed testing regime as described in connectionwith the above discussion of FIG. 8 ) included, in addition to thecontrol: (a) an absorbent pad as shown in FIG. 6B in which two laminatescontaining the individual components of the CO2 generating system areseparated by the absorbent fluff core 400, which contains superabsorbent620; (b) in another embodiment of FIG. 6B, a pad with CO2 generatingcomponents placed in the separate laminates 540A and 540B, with thelaminate closest to layer 200, the permeable layer, containingsuperabsorbent 620; and (c) in another embodiment of FIG. 6B, thecomplete CO2 system is been divided 50/50 between the two separatelaminates 540A and 540B (or it could also be divided in any otherproportions (0-100%/100-0%) in another embodiment), with the fluff layer400 containing superabsorbent load 620. The resultant CO2 generationprofiles can be seen in FIG. 12 , in which the solid line is from acomplete CO2 system contained in a single laminate, the dashed line isfrom the base and acid components of the CO2 system being separated inindividual laminates by fluff 400 containing superabsorbent 620, thedash-dot line is the base and acid components of the CO2 systemseparated in individual laminates by fluff 400, with the base-containinglaminate also containing superabsorbent 620, and the dotted linerepresents the CO2 system split 50/50 into individual laminates 540A and540B separated by fluff 400 containing superabsorbent 620.

FIG. 12A shows another view of how control of CO2 generation effected bythe disclosed structures of FIG. 12 work. FIG. 12A shows the rate ofgeneration of CO2 for the CO2 system split 50/50 embodiment of FIG. 12 ,compared to the control pad of FIG. 12 . In FIG. 12A, two distinctbursts of CO2 are observed for the split structure, compared to oneburst in the single laminate control. This demonstrates that byseparating the individual laminates, the entry of water into the pad canbe controlled to delay the full effects of one laminate to a separate,later time.

Method of making pad. The present disclosure makes use of fluff as onelayer of an absorbent pad. While fluff has been known as an effectiveabsorbent, it has not been used widely in absorbent pads with chemicalsystems incorporated into a laminate or in a combination of afluff-hosted chemical agent or system and a laminate-hosted chemicalagent or system. Applicant found that by mating the fluff with a tissuelayer, in one embodiment a tissue laminate layer, at the point wherefluff is introduced into the manufacturing process provides a substratefor the fluff that allows use of a fluff layer in a range of thicknessesthat makes it both a useful absorbent and a possible carrier of achemical agent or system. Further, it is an absorbent that is flexiblein providing absorbing capacity in absorbent pads as described above.

FIG. 7 shows a schematic diagram of a high speed, web-based padmanufacturing process 700 in which fluff can be used to make absorbentpads. As seen in FIG. 7 the manufacturing line has a mill house 704,which contains a hammer mill with hammers 706. The direction of motionthrough the process is shown by machine direction arrow 701. A sheet ofwood pulp raw material 710 for fluff is fed into the hammers 706 whereit is chopped up and air-formed into a fluff layer of desired thickness,which in the form of a fluff web 708 is fed to an exit from the millhouse 704 on a belt. If desired, a dispenser unit 702 may be placed inmill house 704 for distributing into the fluff web during its formingand/or during transport to an exit a predetermined amount of at leastone chemical agent or system, with the distribution being substantiallyuniform per unit area of an area of the fluff web. (Loading the fluffwith a chemical agent or system may also occur downstream.) Misting maybe used to moisten the exiting fluff web 708. Above the belttransporting the fluff web 708 is located at least one roll 722 of atissue web, in one embodiment a tissue laminate web 720, which is fed tomatch the speed of the fluff web 708 and laid on top of fluff web 708,with these two webs entering the nip of debulk rollers 740. The debulkrollers 740 compress the two webs together, which, aided as needed bymoisture, forms a mechanical bond, such that the tissue laminate 720serves as a substrate for the fluff web 708 in subsequent steps.

The two webs next travel to diamond rollers 742 which provide embossing,then proceed to a station 750 where a top poly layer and a bottom polylayer are applied from web rolls and adhered. The top and bottom polylayers now together with the mated fluff web 708 and tissue laminate web720 are all fed through any desired finishing process and transported tofinal stations 760 for cutting the finished pads and stacking them forshipping.

It will be seen that further layers can be added to the web in thisprocess, e.g., from a further, optional web feed roll 730 (shown inphantom) of tissue laminate web material located just downstream fromroll 722. For example, further web feed roll 730 may be used to feed asecond tissue laminate web 732 on top of the first tissue laminate web720. This can be used to produce the two-laminate layer structure shownin FIG. 6A. Alternatively, by placing further web feed roll 730 underthe mated webs 708, 720 and still located just downstream from roll 722and upstream from debulk rollers 740, the second tissue laminate 732 canbe placed on the opposite (lower, as seen in FIG. 7 ) side of the fluffweb 708. The second tissue laminate 732 then also forms a mechanicalbond, now with the other side of the fluff web 708 to sandwich itbetween laminates, such that the second tissue laminate also serves as asubstrate for the fluff web 708 and adds to the functional layers of theresulting pads. This two-tissue laminate web, whether with the twolaminates adjacent each other or sandwiching the fluff, continuesthrough the remaining stations and steps shown in FIG. 7 .

The present disclosure shows that the various absorbent padarchitectures disclosed herein, with both fluff and tissue laminatelayers capable of being loaded with chemical agents or systems andestablishing flow paths for the liquids absorbed into the pad, lead to apad capable of carrying out actions and reactions that extend the usefullife a food item packaged with such pads. Moreover, the absorbent padarchitectures allow control over dissolution and flow of, and/orreactions using, the loaded chemical agents or systems, including areaction for CO2 generation. The architectures in particular permit thecontrol of liquid flow and/or absorption and of reactions for CO2generation, so the total amount of CO2 generated can be controlled, aswell as the rate of CO2 generation over a period of time designed tocoordinate with the expected useful life of the package. The followingtable assists in presenting some the various structures possible basedon the pad architecture designs disclosed above:

Layer (from top down) 1st Poly or Poly or Poly or Poly or NonwovenNonwoven Nonwoven Nonwoven 2nd Tissue Tissue Tissue Tissue laminatelaminate laminate laminate Tissue Fluff Tissue laminate laminate 3rdFluff Fluff Tissue Fluff laminate Tissue laminate 4th Poly or Poly orPoly or Poly or Nonwoven Nonwoven Nonwoven Nonwoven

As described above, any of the tissue laminate or fluff layers may beloaded with a chemical agent or a system; any layer pair in fluidcommunication may be loaded with one of two components of a two-partsystem dissolvable in liquids entering the pad; and any layer may have asuperabsorbent added to absorb liquids, in some embodiments effectinglater release of absorbed liquids. It will further be understood thattissue laminate layers may be replicated beyond two and fluff layers mayalso be replicated, and that the order of any tissue laminate and flufflayers shown above may be inverted. Additionally, the first and fourthlayers may be comprised of a nonwoven or poly film, or any other of theaforementioned materials described.

What is claimed is:
 1. An absorbent pad comprising: a first, outer layercomprising a permeable or non-permeable material: a second, outer layercomprising a permeable or non-permeable material, placed on a side ofthe pad opposite the first, outer layer; a third layer disposed betweenthe first layer and the second layer, and comprising at least a firstply and a second ply, with at least one chemical agent or system fixedin the third layer and being activated by contact with a fluid, the atleast one chemical agent or system being in a predetermined amountdistributed substantially uniformly per unit area between the at leastfirst ply and second ply; and a fourth layer disposed between the firstlayer and the second layer and comprising fluff, the third layer beingjoined to the fourth layer to serve as a substrate for the fourth layerand being in fluid communication with the fourth layer.
 2. The absorbentpad of claim 1, wherein the fourth layer is disposed between the thirdlayer and the second layer or between the third layer and the firstlayer.
 3. The absorbent pad of claim 1, wherein the third layercomprises at least two plies forming a volume in the third layer loadedwith the at least one chemical agent or system.
 4. The absorbent pad ofclaim 1, wherein the third layer comprises at least two plies of acellulose or cotton-based or similar absorbent-based material.
 5. Theabsorbent pad of claim 1, wherein the fourth layer is a sheet of fluff,with at least one chemical agent or system dispersed in granular form inthe fourth layer, which is activated by fluid.
 6. The absorbent pad ofclaim 1, wherein the first layer or the second layer or both comprises,consists essentially of, or consists of polyethylene, polypropylene,non-woven material or similar material with like properties.
 7. Theabsorbent pad of claim 1, wherein the fourth layer comprises flufffurther comprising a super absorbent material.
 8. The absorbent pad ofclaim 1, wherein the at least one chemical agent or system fixed in thethird layer has a functionality of carbon dioxide generation, superabsorption, ethylene scavenging or inhibiting, oxygen scavenging,odor-removing, color- or taste-removing or changing, or antimicrobialproperties.
 9. The absorbent pad of claim 5, wherein the at least onechemical agent or system embedded in the fourth layer has afunctionality of carbon dioxide generation, super absorption, ethylenescavenging or inhibiting, oxygen scavenging, odor-removing, color- ortaste-removing or changing, or antimicrobial properties.
 10. Theabsorbent pad of claim 1, wherein the at least one chemical agent orsystem fixed in the third layer comprises at least one of: a superabsorbent fiber (SAF); super absorbent polymer (SAP); other superabsorbent material; citric and sorbic acids mixed in about a 64.5:35.5ratio; carbon dioxide chemicals consisting of acid and base in ratio ofabout 43:57 and an ethylene inhibitor or ethylene scavenger.
 11. Theabsorbent pad of claim 9, wherein the at least one chemical agent orsystem fixed in the third layer or the fourth layer has thefunctionality of carbon dioxide generation and comprises at least oneacid and at least one base coordinated with the acid for a CO2generating system.
 12. The absorbent pad of claim 11, wherein the CO2generating system is embedded in the third layer in the followingamounts: weight/in. sq. of an acid component for CO2 generation of about0.042 g/in. sq.; and weight/in. sq. of base component for CO2 generationof about 0.0557 g/in. sq.
 13. The absorbent pad of claim 1, wherein thethird layer comprises two layered plies with CO2 generating chemicalscontaining about 57% base and about 43% acid and a super absorbentmaterial, such as a polymer or a food-safe hydrophilic polymer, such asoptionally cross-linked polyacrylate.
 14. The absorbent pad of claim 1,wherein the third layer comprises two layered plies with at least onechemical agent or system embedded inside with adhesive on one or bothplies, said adhesive being added at a total weight range0.0015-0.0027/ft2 of a resulting two-ply structure.
 15. The absorbentpad of claim 1, wherein the third layer is mechanically joined to thefourth layer to serve as a substrate.
 16. The absorbent pad of claim 1,wherein molecules for activation by absorption or adsorption in the padenter the pad via an adjacent one of the first and second outer layers,via the sides of layers and/or by flow between adjacent layers.